After I flash Angstrom, I get serial access as expected.
After I flash Ubuntu (various versions, including the latest BBB-eMMC-flasher-ubuntu-14.04-console-armhf-2014-08-13-2gb.img, I am locked out. That is: no serial (as expected, I had this with my earlier BBB) but also no SSH to 192.168.7.2 either.
What went before, very briefly: (all via USB)
Power up out of the box, serial on Angstrom OK.
Flash Ubuntu, power down, power up, SSH access on 192.168.7.2 OK. (user ubuntu, pwd temppwd)
Insert root password, power off, power on, SSH access, root login OK
Modify /etc/network/interfaces for Static IP:
#iface eth0 inet dhcp
iface eth0 inet static
dns-nameservers 220.127.116.11 18.104.22.168
This is exactly what I did with my earlier BBB.
After this change, power down, power up.
NO ACCESS via USB. Not in serial mode, not with SSH to 192.168.7.2 or 192.168.0.134
I reflashed several time forth an back to Angstrom, but the result is always: Serial on Angstrom yes, SSH on Ubuntu no.
I can see the BBB as thumb drive with my file browser on the PC, all the files from the uSD seem to be copied to eMMC.
I can open START.htm on the BBB from my file browser, Firefox starts, the “getting started” page is displayed.